1. Field of the Invention
This invention relates to a magnetic head assembly for perpendicular magnetic recording, and more particularly to a magnetic head assembly of the type having magnetic poles on only one side of the magnetic recording medium.
2. Description of the Prior Art
Demands for high density recording are increasing in response to increased amounts of information. In the field of magnetic recording, perpendicular recording systems have been proposed to meet such requirements, and are presently being studied. In perpendicular recording systems, recording is performed in the thickness direction of the recording medium, and unlike conventional in-plane magnetic recording systems, demagnetizing fields do not increase even under a high density recording condition, thus written recording patterns are not demagnetized, and better quality recording can be achieved.
FIG. 7 shows a typical example of conventional perpendicular read/write magnetic head assemblies proposed before (National Convention Record, 1983 the Institute of Electronics and Communication Engineers of Japan, Part 1, p195). This magnetic head assembly has magnetic poles on only one side of the recording medium, and is of the so-called single magnetic pole type. In this type of magnetic head assembly, a recording medium does not need to be supported between the magnetic poles and this arrangement provides good handling. In FIG. 7, a nonmagnetic substrate 1 is provided with a main magnetic pole 2, and an magnetizing core 3 is formed on the main magnetic pole 2. Around the non-magnetic substrate 1, the main magnetic pole 2 and the magnetizing core 3, a read/write coil 4 is wound. An auxiliary magnetic pole 5 is connected onto the end of the magnetizing core 3, which constitutes the return path.
The recording medium 6 may be composed, for example, of a perpendicular magnetizing film 7, a high-permeability magnetic layer 8 and a substrate 9.
In such perpendicular magnetic recording, the magnetization volume of each recording pattern in the magnetic recording medium decreases with the increase of recording density. For this reason, an efficient magnetic head is required. Also, in high density recording, since the information transfer speed is high, the high frequency characteristics of the magnetic head assembly must be improved.
In order to improve the efficiency of the arrangement of FIG. 7, the distance "a" between the magnetizing core 3 and the leg of the auxiliary magnetic pole 5 can be decreased, the width "b" of the leg of the auxiliary magnetic pole 5 can be increased, or the distance "c" between the end of the leg of the auxiliary magnetic pole 5 and the recording medium 6 can be decreased. In these cases, however, pulse noise caused by the edge of the auxiliary magnetic pole 5 facing the recording medium 6 increases and as a result the error rate of the system becomes higher. Also, in order to improve the high frequency characteristics of the magnetic head assembly, the inductance of the auxiliary magnetic pole 5 can be decreased. This can be accomplished by decreasing the distance "a" to decrease the volume of the auxiliary magnetic pole 5. However, even if these changes are made, it is still difficult to obtain an optimum magnetic head in terms of pulse noise.